We recently have released our Power Purifier with built-in Power Cord. This was the result of a request, as to whether we could supply a complete cord, instead of having the extra IEC connections.
This resulted in some mad development along with some interesting discoveries. For example, the effect of dielectrics in the outer sleeve of the cord could ruin the sound of the cord. Cotton was the best, or rather, the least bad. For best performance, you can remove this..
Another was that the low-cost plain copper wire I'd been using sounded pretty good with a very smooth and lush midrange. On the other hand, the Teflon/silver plate that sounded good in the short runs used in Power Purifier could not make a good power cord; there was horrible peakiness in the upper mids/lower highs with a sucked out mid bass. On the other hand, this wire did show that there was detail missing from the treble, and punch from the bass when compared to the normal wire.
I put this down to the silver plate - I'd never been a big fan, and I've used Teflon Kimber for years without this problem. So I started looking for wires that were copper and Teflon.
The first to arrive was some Kimber wire. This was meant to be 15 awg, but seemed somewhat larger, 14 awg at least. This sounds fantastic, with the extra detail of the silver-plate wire, but none of the harshness. This however is expensive - $160 upgrade price for a 1 meter power cord (compared to standard wire).
Around this time, I got some reports from people who had tried the Power Purifier and Power Cord in the USA, using 110/120V. The normal wire is not performing as well as it does in countries with 240/220 VAC. What I've found with wire is that generally it's best to use the thinnest wire you can get away with. Bigger wires mean more inductance, more dielectric effects and so on.
However it became apparent that this wire was not large enough for US voltage use. The problem was that I've tried the larger version of the same wire and it sucks. So I needed something else.
Then the second Teflon/copper cable arrived. This one was not designed for audio, and is much cheaper than the Kimber. Initial tests are very promising, but as this wire only arrived yesterday, there's a lot more testing to be done yet. The wire we have now is 13awg, and there is some 11awg on order, which I hope will be ideal for US Power Cords. I hope these will be available mid-April. Prices have not been finalized yet, but are likely to be $20-$40 range to upgrade a Power Cord.